Manganese blank

Klinkhammer [432] has described a method for determining manganese in a seawater matrix at concentrations ranging from about 30 to 5500 ng/1. The samples are extracted with 4 nmol/1 8-hydroxyquinoline in chloroform, and the manganese in the organic phase is then back-extracted into 3 M nitric acid. The manganese concentrations are determined by graphite furnace atomic absorption spectrophotometry. The blank of the method is about 3.0 ng/1, and the precision from duplicate analyses is 9% (1 SD). 

Tc and Re are Mendeleev s eka-manganese and dvi-manganese, which he recognized as blank spaces in his... 

Set-up and optimise the AAS instrument for determinations of zinc. Calibrate the instrument with the zinc working standard solutions and measure the concentration of zinc in all the blank, check and sample solutions, as for manganese. 

Fig. 2. Recorder trace for the determination of manganese in serum by GF-AAS. Method as described in the text. Duplicate injections of A-D, standards of 0, 1, 2 and 3 /

Prepare standards of 0, 2, 5 and 10//g/L manganese in 0.1% v/v Triton X-100 solution. Dilute a blood sample low in manganese 1 -t- 3 with the standards to prepare calibration solutions equivalent to 0, 6, 15 and 30 //g/L manganese in the blood samples. Samples are diluted 1 -l- 3 with the zero standard. A blank of distilled water diluted similarly is also prepared. 10 //L aliquots of prepared standards, blank and samples are analysed in duplicate in the furnace using the programme for serum shown in Table 2. Subtract the peak absorbance of the standards from the value for the zero standard and plot a calibration curve. From the peak absorbances of the samples, subtract the value for the reagent blank and read the concentration from the calibration cun/e. 

Conduct a reagent blank test in the same way. For this purpose take 28 ml of saturated SO2 solution and continue treatment as for the corresponding SO2 solution of the analysis sample in which the manganese dioxide hydrate was dissolved. 

For the determination of reagent blank (.Arb) proceed exactly as described for iron (Section 12.5.1.6). The numerical value of is also about the same as that for Fe. To correct for colour and/or turbidity pour the sample from the cuvette back into the reaction flask and add 0.5 mL of about 5 mol/L sulphuric acid. The acid destroys the manganese complex. By reading the absorbance of this acidified sample, a measurement of colour/turbidity is obtained. 

To detect magnesium in the presence of manganese, 2 drops of the test solution are treated with colorless ammonium sulfide and, without heating, the suspension is centrifuged. The supernatant liquid is transferred to a spot plate by means of a capillary siphon and treated with the dyestuff solution. The latter is reduced within a few minutes by the excess ammonium sulfide to form a red aminoazo dye. It is therefore essential to carry out a blank test. 

It must be noted that ammoniacal silver solutions are slightly reduced to metaUic silver by filter paper. Consequently a blank test is essential for small amounts of manganese. 

Procedure II. A drop of the copper-manganese solution and a drop of sodium hypobromite solution are added to a drop of the test solution in a micro test tube. A blank test on water plus the reagents is set up. Both tubes are heated for a few minutes in boiling water, or are brought to boiling over a flame. In the presence of telluric acid, the test solution becomes colorless or slightly yellow, while the blank test assumes the permanganate color. 

Measure the extinctions of the sample and blank solutions at the absorption maximum at about 526 m using 1-cm cells with water in the comparison cell in each case, read the fJLg manganese equivalent to the extinctions from a standard curve and so obtain the net manganese content of the sample. 

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